[mor1matt]

Hi everyone

i just bought my first alfa yesterday and really happy done about 200 miles in it already:thumbs:, but just today on the way home the battery died. i checked the battery and only showed 6 volts with a multimeter. i charged it for a bit and managed to get it started. do you think it's worth me getting a new battery or is it a fault with the alternator??

 

[allblack156]

what does battery read when engine running??

 

[symon]

Get the car started and measure the voltage across the battery terminals with the engine running.

If you are getting around 13-14v then your Alternator is most probably ok.


A knackered battery won't usually make a car stop once it is running, but a knackered alternator will make it stop once it has allowed the battery to go flat.

 

[mor1matt]

it was about 6.7 volts once i got the engine running

 

[alfa-mick]

if you have a multimeter you should be able to tell exactly which is at fault. if the battery is showing a voltage of 12.6 or above when the engine is running your alternator should be working ok.

 

[allblack156]

Well should be reading between 13/14v with engine running .. so probably alternator but check for bad earths 1st....

 

[symon]

it was about 6.7 volts once i got the engine running

Was the charge warning light illuminated on the dash?

If it was it sounds like your alternator is the problem.

 

[alfa-mick]

best way to tell is leave the car overnight and without starting it check the voltage on the battery with multimeter. then start the car and if the voltage increases the alternator is working.

 

[mor1matt]

had no charge light show up at all but before it died, i had the abs warning light come up, then all the lights and the stereo turned off. after charging, still had no lights come up for the alternator and everything is ok. will check in morning and take the voltage again with the multimeter

 

[symon]

You will get all sorts of lights and warnings come up if the battery voltage drops.

I am hoping it is the battery for you, as that is the easier and cheaper fix. Batteries do tend to die in the winter.

 

[mor1matt]

i'm hoping it's the battery too, don't fancy changing the alternator in this cold weather!!

 

[RBaron]

>>A knackered battery won't usually make a car stop once it is running,<<

Did, though, didn't it. The fuel pump requires a surprising amount of power.

mor1matt...things dying inside the car. That's exactly what happens when the battery voltage drops off. all of the unimportant stuff gets disengaged first - even your main beam will stop.

I had exactly this. Was a loose connection to/from the alternator for me.

 

[mor1matt]

this morning, i've changed the battery and all seems ok for the mo. haven't taken a reading with the multimeter yet as had no time. hopefully it will read about 14 volts

 

[symon]

>>A knackered battery won't usually make a car stop once it is running,<<

Did, though, didn't it. The fuel pump requires a surprising amount of power.

mor1matt...things dying inside the car. That's exactly what happens when the battery voltage drops off. all of the unimportant stuff gets disengaged first - even your main beam will stop.

I had exactly this. Was a loose connection to/from the alternator for me.

It depends on the car and the battery.

My 146Ti ran with a totally stuffed battery as did my GTV.

 

[mor1matt]

i'm gonna check the voltages tonight! if it's ok then will put it down to the battery not taking any charge. but will check the alternator connections, i believe i've got to jack up the car to get to it?

 

[mor1matt]

managed to take the voltage with the engine off and on. with engine off it's 11.97V and with the engine on it's 11.80v to 11.82v.

 

[symon]

managed to take the voltage with the engine off and on. with engine off it's 11.97V and with the engine on it's 11.80v to 11.82v.

That doesn't soound too good to be honest.

The voltage should be above 12V and probably nearer 14V with the engine running.


I think you may have a dodgy alternator. The car will probably drive fine for a while but the battery will go flat and the car will stop.


Yes you do need to get at the alternator from underneath unless you fancy taking the inlet manifold off.

 

[mor1matt]

thought it would be the alternator, how hard is it to change it from underneath?

 

[symon]

To be honest I have never changed one, but I cannot see it being too easy.

It might be an idea to start another thread asking how to remove it.
I have a feeling you will need to drop the subframe as there isn't much access to it.

 

[armoore]

Is the battery light illuminating with ignition on but engine not running? If not the bulb is u/s. On some charging systems I've seen if the warning light fails then the charging circuit is incomplete too! Strange but true. A bulb should be easier to change than an alternator. There are a number of threads regarding alternator replacement, do a search but I don't think it is that easy.